Machine-Type Communication (MTC) is an important revenue stream for operators and has a huge potential from the operator perspective. Lowering the cost of MTC user equipment (UEs)/devices is an important enabler for the implementation of the concept of “Internet of Things” (IOT). Many MTC devices are targeting low-end (low average revenue per user, low data rate) applications that can be handled adequately by GSM/GPRS. Owing to the low-cost of these devices and good coverage of GSM/GPRS, there is very little motivation for MTC UE suppliers to use modules supporting the LTE radio interface. In order to ensure that there is a clear business benefit to MTC UE vendors and operators for migrating low-end MTC devices from GSM/GPRS to LTE networks, a new type of terminal, i.e. a low cost (LC) MTC UE, is introduced in Rel-11. The cost of the LC-MTC UEs is tailored for the low-end of the MTC market to be competitive with that of GSM/GPRS terminals. The LC-MTC UEs are characterized by: 1) One Rx antenna; 2) Downlink and uplink maximum TBS size of 1000 bits; 3) Bandwidth reduction (BR)—resources for each channel transmission are limited to contiguous 6 PRBs (1.4 MHz) for cost reduction, and 4) Coverage enhancement—some applications of LC-MTC UEs will require 15-20 dB coverage extension and repeated transmission is a common technique to compensate penetration losses.
In LTE Rel. 12, it is shown that the implementation of half-duplex FDD (HD-FDD) MTC with single received antenna is cost-competitive. The bandwidth reduction technique can offer further cost reduction. The UE with bandwidth reduction (BR-UE) can be implemented with lower cost by reducing the buffer size, clock rate for signal processing, and so on. However, it also faces many challenges when the BR-UE tries to camp on the LTE cell of which cell bandwidth is larger than the supported bandwidth of its bandwidth. In LTE, the control channels including PCFICH, PHICH and PDCCH span over whole bandwidth. When the supported bandwidth at the BR-UE is less than cell bandwidth indicated by PBCH, the BR-UE is only capable of decoding PBCH and PSS/SSS allocated in center 6 PRB pairs. The BR-UE is not able to decode SIBs, PDSCH, RAR, or Paging due to lack of ability of decoding control channels. Novel control channel designs are needed to make the BR-UE be able to camp on the LTE cell.
When there are too many BR-UEs, it is impossible for the serving eNodeB to schedule all BR-UEs at center 6 PRB pairs. Consequently, the serving eNodeB may try to schedule different BR-UEs at different PRB pairs. In these cases, the BR-UE that is not scheduled at the center 6 PRB pairs is unable to perform intra-frequency measurement for handover and Reference Signal Time Difference (RSTD) measurement. Therefore, methods for intra-frequency/RSTD measurement are needed.
Moreover, the BR-UE cannot offer the channel quality report of whole downlink (DL) cell bandwidth. The BR-UE cannot measure the wideband CQI at single subframe. Therefore, methods to assess the whole bandwidth are needed such that the serving eNodeB can schedule BR-UEs in efficient manner.